β-Hydroxybutyrate is the preferred substrate for GABA and glutamate synthesis while glucose is indispensable during depolarization in cultured GABAergic neurons

► Glucose and β-hydroxybutyrate metabolism were studied in cultured neurons using 13C. ► β-Hydroxybutyrate inhibits metabolism of glucose in GABAergic neurons. ► β-Hydroxybutyrate cannot substitute for glucose as energy substrate during activity. ► The presence of β-hydroxybutyrate affects aspartate but not GABA content. ► 13C in glutamate and GABA coming from β-hydroxybutyrate exceeds that from glucose.